Project description:Differential gene expression in a wide range of tissues including brown adipose tissue (BAT), liver, heart, hypothalamus, and skeletal muscle in hibernating arctic ground squirrels during multiple stages in torpor-arousal cycles compared to non-hibernating (post-reproductive) animals with illumina beadarray technology. Keywords: Multiple stage comparison
Project description:Differential gene expression in a wide range of tissues including brown adipose tissue (BAT), liver, heart, hypothalamus, and skeletal muscle in hibernating arctic ground squirrels during multiple stages in torpor-arousal cycles compared to non-hibernating (post-reproductive) animals with illumina beadarray technology. Arctic Ground Squirrels were sampled at four stages of hibernation: early arousal denoted as EA (1-2 hrs after Tb cross 30¡C, n=4), late arousal denoted as LA (7-8 hrs after Tb cross 30¡C, n=4), early torpor denoted as ET (10-20% of torpid episode, n=4) and late torpor denoted as LT (80-90% of torpid episode, n=5), where Tb is the body temperature and the length of torpid episode is estimated from the previous torpor bout. Post-reproductive animals denoted as PR (n=7) were used as non-hibernating control. Five tissue types: brown adipose tissue (BAT), liver, heart, hypothalamus, and skeletal muscle were hybridized on two customized 700-gene beadarray platforms: 1A and 2A on 96-sample Illumina ArrayMatrix. The data of a pilot study involving brown adipose tissue (BAT), liver, and skeletal muscle on 16-sample Illumina BeadChip denoted as 16chip are also included in this series.
Project description:Hibernation is an energy-saving strategy adopted by a wide range of mammals to survive highly seasonal or unpredictable environments. Arctic ground squirrels living in Alaska provide an extreme example, with 6-9 months long hibernation seasons when body temperature alternates between levels near 0 C during torpor and 37 C during arousal episodes. Heat production during hibernation is provided, in part, by non-shivering thermogenesis that occurs in large deposits of brown adipose tissue (BAT). BAT is active at tissue temperatures from 0 to 37 C during rewarming and continuously at near 0 C during torpor in subfreezing conditions. Despite its crucial role in hibernation, the global gene expression patterns in BAT during hibernation compared to the non-hibernation season remain largely unknown. We report a large-scale study of differential gene expression in BAT between winter hibernating and summer active arctic ground squirrels using mouse microarrays. Selected differentially expressed genes identified on the arrays were validated by quantitative real-time PCR using ground squirrel specific primers. Our results show that the mRNA levels of the genes involved in nearly every step of the biochemical pathway leading to non-shivering thermogenesis are significantly increased in BAT during hibernation, whereas those of genes involved in protein biosynthesis are significantly decreased compared to the summer active animals in August. The differentially expressed genes also include those involved in adipose differentiation, substrate transport, and structure remodeling, which may enhance thermogenesis at low tissue temperatures in BAT. Keywords: hibernating animals vs. summer active animals
Project description:miRNAs are 19-25 nucleotides long small RNAs now well-known for their regulatory roles in the development and diseases through post-transcriptional and translational controls in a wide range of species. Mammalian hibernation is a physiological process involving dramatic metabolic suppression and cellular reorganization, during which miRNAs may play an important role. We systematically analyzed the miRNAs in the liver of an extreme hibernating species, arctic ground squirrels (Spermophilus parryii), during two stages of hibernation compared to non-hibernating animals by massively parallel Illumina sequencing technology. We identified more than 200 ground squirrel miRNAs including novel miRNAs specific to ground squirrel and a fast-evolving miRNA cluster that also showed significant differential expression during hibernation. Integrating with Agilent miRNA microarray and Real-time PCR results, we identified that mir-211, mir-378, mir-184, mir-200a, and mir-320 were significantly under-expressed during hibernation, whereas mir-144, mir-486, mir-451, mir-142-5p, and mir-1 were over-expressed. Analyses of the their target genes suggested that these miRNAs could play an important role to suppress tumor progression and cell growth during hibernation. Investigation of microRNA changes in arctic ground squirrel livers during Early Arousal(EA), Late Topor(LT), and Post-Reproduction(PR) stages.
Project description:miRNAs are 19-25 nucleotides long small RNAs now well-known for their regulatory roles in the development and diseases through post-transcriptional and translational controls in a wide range of species. Mammalian hibernation is a physiological process involving dramatic metabolic suppression and cellular reorganization, during which miRNAs may play an important role. We systematically analyzed the miRNAs in the liver of an extreme hibernating species, arctic ground squirrels (Spermophilus parryii), during two stages of hibernation compared to non-hibernating animals by massively parallel Illumina sequencing technology. We identified more than 200 ground squirrel miRNAs including novel miRNAs specific to ground squirrel and a fast-evolving miRNA cluster that also showed significant differential expression during hibernation. Integrating with Agilent miRNA microarray and Real-time PCR results, we identified that mir-211, mir-378, mir-184, mir-200a, and mir-320 were significantly under-expressed during hibernation, whereas mir-144, mir-486, mir-451, mir-142-5p, and mir-1 were over-expressed. Analyses of the their target genes suggested that these miRNAs could play an important role to suppress tumor progression and cell growth during hibernation. Three total RNA pools from arctic ground squirrel livers in Early Arousal(EA), Late Topor(LT), and Post-Reproduction(PR) stages were hybridized to three Agilent mouse miRNA microarrays.
Project description:Hibernation is energy saving adaptation involving suppression of activity to survive in highly seasonal environments. Immobility and disuse generate muscle loss in most mammalian species. In contrast to other mammals, bears and ground squirrels demonstrate limited muscle atrophy over the physical inactivity of winter hibernation. This suggests that hibernating mammals have adaptive mechanisms to prevent disuse muscle atrophy. To identify common transcriptional program underlying molecular mechanisms preventing muscle loss, we conducted a large-scale gene expression screening in hind limb muscles comparing hibernating and summer active black bears and arctic ground squirrels by the use of custom 9,600 probe cDNA microarrays. The molecular pathway analysis showed an elevated proportion of overexpressed genes involved in all stages of protein biosynthesis and ribosome biogenesis in muscle of both species during hibernation that implies induction of translation at different hibernation states. The induction of protein biosynthesis likely contributes to attenuation of disuse muscle atrophy through prolonged periods of immobility and starvation. This adaptive mechanism allows hibernating mammals to maintain full musculoskeletal function and preserve mobility during and immediately after hibernation, thus promoting survival. The lack of directional changes in genes of protein catabolic pathways does not support the importance of metabolic suppression for preserving muscle mass during winter. Coordinated reduction of multiply genes involved in oxidation reduction and glucose metabolism detected in both species is consistent with metabolic suppression and lower energy demand in skeletal muscle during inactivity of hibernation. Arctic ground squirrels sampled during winter hibernation were compared with the animals sampled during summer. Muscle was hybridized on a custom 9,600 probes nylon membrane microarray platform. Ten in late torpor, four in early arousal, then in late arousal were studied in experiments.